A west Hull boiler firm is looking into closing part of its manufacturing operation in favour of overseas contractors.
Ideal Boilers is carrying out a feasibility study into shutting its century-old foundry at its site in National Avenue.
According to sources, dozens of jobs could be lost if the decision is taken to close the foundry, which is used to cast heat exchangers for boilers.
It was installed in 1905 when the firm was part of the National Radiator Company.
One worker, who wanted to remain anonymous, said company managers announced several weeks ago they would be looking into the economics of keeping the foundry running.
He said: "Apparently they are thinking of closing it and importing the heat exchangers."
The employee said closing the foundry would have a knock-on effect to other areas of the business.
He said: "It wouldn't stop there.
"The machine shop, tool room and cleaning room would also be affected."
Earlier this month Ideal Boilers announced 30 redundancies due to falling sales volumes.
The figure brings the number of losses at the firm to 103 this year.
Remaining staff have been on shortened working weeks since September and some have seen their salaries more than halved since that time.
Earlier this month it was announced the firm was closing 200 branches of the Plumb Centre business, which is believed to be a major customer of Ideal Boilers.
According to sources, Ideal Boilers is overstocked by thousands of boiler units as a result of falling sales, meaning production at the factory is being scaled backed.
Ken Vincent, regional organiser for the GMB union, said it was unclear where the company would import heat exchangers from if the foundry was to shut.
Options are believed to include Turkey or China, depending on cost.